They may be able to acclimate to pH, but hardness is another thing. It directly impacts the health of the fish. Do you know how hard your water is?
Kuhli loaches haven't been commercially produced yet, so unless you are buying them for a REALLY lucky breeder, then they were wild caught and need to be at a pH under 7. Most loaches in the aquarium industry haven't been bred on a commercial scale yet. Home breedings have been accomplished but only very rarely.
I can't tell if you're going for neon tetras or cardinal tetras. Cardinal are more sensitive and will look soo much better in an acidic pH. Neon tetras are hardier and should survive at your pH, but they won't look as pretty as they could.
I ran your stocking plan through AqAdvisor (a great place to start, but not the final say) and this is what it had to say: Suggestion: If you want to keep more than 1 Guppy, minimum recommend male to female ratio is 1:2 (M:F). You will be less likely to experience problem if you get even more females.
Warning: At least 5 x Kuhli Loach are recommended in a group.
Recommended temperature range: 24 - 27 C. [Display in Farenheit] Recommended pH range: 6 - 7.5. Recommended hardness range: 5 - 15 dH. Warning: You NEED to add more aquarium filtration capacity!!!
Your aquarium filtration capacity for above selected species is 46%
Recommended water change schedule: 33%
per week. Your aquarium stocking level is 125%
. [Generate Image] AqAdvisor
Go play around with it if you like.